Assessment of Lymphedema Risk Following Lymph Node Dissection and Radiation Therapy for Primary Breast Cancer

Lymphedema is a common, chronic, and potentially devastating complication of primary breast cancer therapy. Radiation increases patients lymphedema risk up to 36% as conventional fields irradiate vital lymphatic tissues. Fusion imaging technologies that combine anatomical and physiological data, e.g. SPECT/CT, may identify lymphatics critical for arm drainage and allow the creation of conformal radiation treatment fields that minimize the exposure of lymph nodes (LNs) and vessels while delivering therapeutic doses to target tissues. This study uses SPECT/CT scanning to localize lymphatics critical for arm drainage, and has established the feasibility of fusing SPECT/CT images with the CT scans used for radiation planning, thereby creating the opportunity to spare essential LNs needless radiation. The research for this project was conducted in two phases. The first involved estimating the levels of incidental, non-therapeutic radiation delivered to the lymph nodes essential for arm drainage following axillary surgery for breast cancer. The second involved estimating the dose reduction in levels of incidental radiation to critical arm-draining lymph nodes that could be achieved by integrating SPECT/CT images into the radiation planning process. In the second study, among 28 patients the mean lymph node radiation exposure was 23.6 Gy (SD 18.2) with the standard and 7.7 Gy (SD 11.3) with the SPECT/CT modiifed plans (p 0.001). These studies realized the BCRP goals by elucidating a novel means of refining breast cancer treatment to minimize patients' risk of developing the most prevalent and dreaded complication of conventional therapy, lymphedema.
The original document contains color images.